There is a national interest in the discovery of alternative sources of fuels and chemicals, other than from petroleum resources. As the public discussion concerning the availability of petroleum resources and the need for alternative sources continues, government mandates will require fuel range hydrocarbons to include, at least in part, hydrocarbons derived from sources besides petroleum. As such, there is a need to develop alternative sources for hydrocarbons useful for producing fuels and chemicals.
One possible alternative source of hydrocarbons for producing fuels and chemicals is the natural carbon found in plants and animals, such as for example, oils and fats. These so-called “natural” carbon resources (or renewable hydrocarbons) are widely available, and remain a target alternative source for the production of hydrocarbons. For example, it is known that oils and fats, such as those contained in vegetable oil, can be processed and used as fuel. “Bio-Diesel” is one such product and may be produced by subjecting a base vegetable oil to a transesterification process using methanol in order to convert the base oil to desired methyl esters. Oils and fats have also been successfully hydrotreated to produce hydrocarbons/fuel range hydrocarbons, which are called “Renewable-Diesel”.
However, oftentimes, vegetable oil and fats can contain certain amount of free fatty acid. In addition, triglycerides that make up the bulk of both oils and fats may break down under heated conditions to produce additional free fatty acid. Although free fatty acid can be converted to hydrocarbon in the hydrotreater, they may cause potential corrosion issues in the upstream portion of a hydrotreating unit, such as, but not limited as, in a heat exchanger and/or feed/storage tank.
For crude oils and fractions containing carboxylic acids, commonly referred to as naphthenic acids, most refiners either dilute the acids with low acid feedstock, which requires buying more expensive non acidic crude, or upgrade metallurgy to alloys, which are resistant to the corrosion caused by these acids. These methods require substantial cost.
As such, development of a process for producing hydrocarbons from triglycerides, such as vegetable oils or fats, with reduced potential corrosion and avoided metallurgy upgrading would be a significant contribution to the art and to the economy.